عنوان مقاله [English]
Coastal wetlands are known as the most dynamic, productive, and appreciated of the whole ecosystems nonetheless involve merely 15 per cent of total wetland areas on the Earth (Isunju et al. 2016). The ecological and social profits of wetlands are typically recognized as ecosystem services that these ecosystems make to human well-fare (Sarkar et al., 2016). Scientists have noticed the proficiencies of these environments to respond impacts of global warming (Endter-Wada et al., 2020). However, the relationship between wetlands and human society has differed meaningfully during the time (Land et al., 2016). Wetlands have suffered an excessive encounter principally due to human activities and anthropogenic stressors, such as population growth, industrial and economic development, introducing species, aquaculture, agriculture, and tourism (Cui et al., 2016). Therefore, wetlands are the greatest threatened ecosystems with quicker rates of ruin than other ecosystems (Boon et al., 2015). Damages are associated with human activity pressures such as landscape modification and conversion for agriculture, urbanization, industrial development, climate changes, and sea-level rise (Mohebbi et al., 2021). In order to conserve wetland and its biodiversity, the managerial process would be required that is carried out with a detailed interpretation of problems and ecosystem approach; the importance of such tools has increasingly been recognized by both academic researchers and environmental managers (Grechi et al. 2016). Since environmental managers and planners used Ecological Risk Assessment (ERA) for the wetland alteration (Raimondo et al. 2019). An ERA is a multifarious process to analyse innumerable ecological, socio-economic, and managerial variables (Sarkar et al. 2016) that can offer a systematic framework for managing risks in the wetlands and their surrounding area (Zhai et al. 2017). ERA has been distinguished as a superior tool to categorize and prioritize risks caused by stressors and has globally developed a broadly acknowledged procedure for monitoring and managing wetlands (Mohebbi et al., 2021). ERAs are generally classified into two types of analysis including predictive and or retrospective. Predictive risk assessment emphasizes the relationship between the pollution sources, the stressors distribution, the exposure of organisms, effects of the toxicity, and managerial responses (Tian et al., 2018). The approach of this analysis is to find cause-effect relationships between stressors and perceived ecological effects (Li et al., 2020). Therefore, the Tier Ecological Risk assessment (TIER) model is a hierarchical process is usually used to practice ERA on wetlands that can show a better understanding of how the stressors inter wetlands (Ai et al., 2021). However, it is essential to realize that ERAs will still need to be designed on a location or chemical particular basis to define and solve the specific concerns (Wang et al., 2019). This study applied a hybridized and tiered method to assessing risks in combined with MIKE 21 computerized model and geographic information system for simulating and zoning risks on the wetland area. The global intergovernmental Ramsar Convention on Wetlands conservation has further proposed risk assessment techniques combined with GIS as a potentially useful model for risk management in the East Kolkata Wetland Area and ultimately concluded that the combinatorial models are efficient and can show the various levels of wetland risk zones by map (Sarkar et al., 2016) in addition some mathematical formula is applied to estimate and prioritize risks (Niemeyer et al. 2015). Likewise, water quality takes effect by the pollution sources around the wetland (Mahdi et al., 2021) and pollutants are significant stressors in aquatic ecosystems that can conclude various changes in species life based on their threshold (Riva et al., 2019). MIKE is known as a software series that has an assortment of approaches to aquatic environment issues (Ahn et al., 2019) it is driven by the Hydrodynamic Module (HD) for flow modelling, Transport Module (TM) for pollution transport modelling, and GIS to display water pollution distribution as well (Nirwana et al., 2021). Li et al. (2020) have improved the Mike 21 model precision for counting the actual position of pollution in the Donghu Lake in China, by using remote sensing (Li et al., 2020). According to the main target of this study, wetland conservation and alteration the conceptual model of pressure-status-response (PSR) is applied for ecological risk management (Harwell et al., 2019). In this paper, Boujagh National Park and International Wetland have opted to identify human activities and risks. Boujagh is located in the Southwest of the Caspian Sea shoreline and the north of Iran, as a case study. Stressors such as nitrogen, phosphor, heavy metals, toxic components, detergents, and other substances have confronted significant species to the risks. For instant Caspian Seal (Phoca caspica), white-fronted goose (Anser albifrons), red-breasted goose (Branta ruficollis), dalmatian pelican (Pelecanus crispus), white-tailed eagle (Haliaeetus albicilla) (Ashoori, 2018), and starry sturgeon (Acipenser stellatus) (Mohebbi et al., 2021) are classified as protected species and others such as kingfisher (Alcedo atthis), pygmy cormorant (Phalacrocorax pygmeus), swans, ducks, crane, flamingoes (Ashoori, 2018), brown trout (Salmo trutta), amphibians (Rana. spp and Bufo. spp), and reptiles (Mohebbi et al., 2021). The current study aims are to focus on the effect of the intensity and location of anthropogenic activities on coastal wetland ecosystems by an ecological risk assessment that can probe any changes in detail. This study has been carried out in Boujagh Wetland in 2020.
Results indicated agricultural areas, aquaculture, residential wastewater, and recreational utilization are distinguished as the most significant pollution sources in the study area. The proportion of pollution sources in the wetland area and the upstream river is classified including the agriculture sector, industrial section, urban and residential parts, and aquaculture with 69, 13, 11, and 7 percentages, respectively. There are several types of stressors in the wetland area. The amount of BOD in summer would be much higher than the others. DO would have its lowest value in summer and its changes in other seasons have not been very significant. In addition, phosphorus in the form of phosphate (PO43-) can be absorbed by phytoplankton. As a result of the simulation, there is not a forecasted considerable difference between the various concentrations of phosphorus in different seasons. Examination of the nitrate (NO3-) simulation shows that the amount of this parameter is less than the standard of water quality. Analysis of ammonia (NH4) concentration shows that the concentration of this contaminant in summer was predicted in the highest amount and for other seasons did not fluctuate remarkably. Results show that the concentration of this parameter is in the range of water quality standards and is almost suitable for general applications. Overlaying MIKE 21 results and several maps of the natural environment could sum up the location of ecological risks in the study area, sensitive areas layer, ecologically important wildlife species, significant invertebrates, as well as vegetation, have been used for this target. Regarding the study results, chemical stressors would have various effects on the organisms throughout the ecosystem, although the threshold of any species depends on its LC50, LD50, NOEL, or NOEC, toxicity would remain in its body texture and is transmitted during the food web to the next species that feeds on it.
Overall, almost 42 per cent of the wetland area has faced with high-level ecological risks, were covered the sensitive habitats and location of aquatic species and immigrant birds, in the second rank, 29 per cent of ecological risks have merged in very high-level class. These are located on shoreline areas, as well as a breeding site in the Sefidrood delta, and the edge of the river. In addition, the place surrounded by solid wastes in the landfill site is exposed to a dangerous condition, which is recommended to replace. Although the wetland area is very sensitive, there are identified 9 per cent of the risks in a low level. Other remaining places have been categorized as having a moderate risk level with 20 per cent. Negligible risk level has not been located in this area.
Ultimately, to reduce risks and manage environmental issues, risk management has been conducted in the PSR model. Utilization of wetland and upstream basin is remarkable pressure on the area such as agriculture pollutants, fishery, land taking, aquaculture, industrial and residential pollutions, polluted sediments, military manoeuvre, boating, building, irregular recreation, and exotic species which properly generate significant deviations on the wetland existing status. Hence, there is necessary to establish a systematic, comprehensive, and integrating environmental management to conserve the wetland area and its upstream catchment. Therefore, conversation and integrated management system has been suggested as the key response, and also to improve the existing status, some main reactions have been identified such as managerial organization, site protections, budget providing, principle recreation policy-making, wisdom utilization with ecological approach, monitoring, auditing, public participation in the Boujagh national park and wetland, implementation Ramsar Convention regulations, providing environmental water demand, ecological capability assessment, and rehabilitation and restoration potential assessment.